498 EXPERIMENTAL PHARMACOLOGY 



Lacquering. It often happens that one wishes to pre- 

 serve the appearance of a new piece of apparatus and to 

 prevent oxidation of the metal. For brass articles this can 

 often be readily done by lacquering. A good coat of lacquer 

 is often more satisfactory than nickel plating for the nickel 

 is very liable to corrode in the atmosphere of a laboratory. 



Lacquering can only be done satisfactorily after the metal 

 has been well burnished and polished. This is done by means 

 of cloth (or felt) buffing wheels (costing about 25 to 50 

 cents apiece), which are turned at a high speed (2000 or 

 more revolutions per minute) while the metal articles are 

 held against the rotating edge of the wheel. The buffing 

 wheels can usually be placed on the same head as that used 

 to turn the (power) emery wheel. Or the buffing wheel may 

 be placed on an arbor which can be held in the chuck of a 

 lathe and turned at the highest speed obtainable with the 

 lathe. For the first or coarse buffing a substance called 

 tripoli (which resembles a bar of soap into which a large 

 amount of powdered pumice stone had been mixed while the 

 soap was melted) is rubbed on the buffing wheel. The metal 

 instrument is then brought against the wheel and is quickly 

 rubbed smooth, and file scratches, etc., may be completely 

 removed by grinding off the outer layers of the metal. The 

 finer polishing is then finished on a second (cloth) wheel 

 to which a substance called rouge (resembling a very fine, 

 dry, reddish bar of soap containing a still finer powder of 

 pumice stone) is applied. This wheel gives the brass a very 

 high degree of polish and the instrument should be wiped 

 off with a clean, dry towel after this buffing is completed. 



The best lacquer the author has used was obtained from 

 the Kahlbaum chemical works and was called metall furniss 

 (Hocli gold). This lacquer should be diluted several times 

 with pure ethyl alcohol. A very thin solution is thus ob- 

 tained and should be applied very quickly with a wide, flat 

 camel's hair brush. Small articles can best be dipped into 

 the solution. Drying should occur very rapidly and it is 

 usually not possible to overlap two separate coatings of the 



